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What is alumina used for? Introduction to the role of alumina
Aluminum oxide is also aluminum oxide, commonly known as bauxite, corundum, and aluminoxy. It is a white powder that is insoluble in water. There are many synthesis methods for aluminum oxide, the common ones are acid method, alkali method and alcohol-aluminum method. In my country, it is mainly synthesized by alkali method, and some manufacturers use alcohol-aluminum method, and the adoption rate of acid method is relatively small. In addition, it can also be obtained by dehydrating aluminum hydroxide at high temperature. So what is the use of aluminum oxide after it is made? Let's take a look at the function of aluminum oxide.
1. Used as catalyst and catalyst carrier, it is the main catalyst and carrier in petroleum refining and petrochemical industry. Also used as dehumidifier for air and other gases, deacidifier for transformer oil and turbine oil.
2. High temperature furnaces for forging heating furnaces, soaking furnaces and other industrial uses. Can be used as sealing materials and filling materials. It can also be used as reinforcing fibers for strengthening, furnace linings for kilns, calcination furnaces for electronic components (IC plates, ferrite), etc.
3. Alumina fiber is mainly used for high temperature thermal insulation materials and reinforced composite materials. Alumina short fiber has outstanding high temperature resistance. It can be combined with resin, metal or ceramics to prepare high-performance composite materials, and manufacture industrial high-temperature furnaces such as heating furnaces, kiln liners and calciners for electronic components. Due to its low density. Good thermal insulation and small heat capacity, it can not only reduce the quality of the furnace body, but also improve the temperature control accuracy, and the energy saving effect is remarkable. The energy saving effect of alumina fiber in high-temperature furnaces is better than that of ordinary refractory bricks or high-temperature coatings. When it is used to strengthen metal, it has no chemical effect with metal at all and has good corrosion resistance, so alumina fiber is the reinforcing fiber of metal. It can also be used to weave fiber products of various shapes such as non-woven fabrics, woven belts, and ropes.
4. Used in the manufacture of heating furnaces, soaking furnaces and other industrial high-temperature furnaces. Used as sealing materials, filling materials, reinforced fibers for FRM, kiln liners and calciners for electronic components (IC substrates, ferrite), etc.
5. Mainly used as chemical fiber filler, and also used in abrasive of cosmetic facial paste, toothpaste friction agent, metallurgy and chemicals.
6. Preparation of analytical reagents, dehydrated adsorbents for organic solvents, abrasives, and low melting point lead glass.
7. Alumina is the most commonly used filler material in chromatography, with acidity, alkalinity and neutrality. It is a reagent capable of catalytic dehydration, elimination, addition, condensation, epoxide ring opening, oxidation and reduction reactions. For homogeneous reactions, the reaction conditions are usually milder and more selective.
8. Addition and Condensation Reactions Whether it is an electrophilic reaction or a nucleophilic reaction, alumina can promote the addition reaction of various heteroatoms. Alumina can also cause intramolecular addition of hydroxyl and alkoxy groups to generate corresponding olefins. Under the action of alumina, the alcohol-aldehyde condensation reaction, Michael reaction and Wittig reaction between aldehyde and methylene compounds with different activities are often carried out under solvent-free and mild conditions. The reaction of cyclization of nitroaldehyde to 2-iso-azoline 2-oxide has good stereoselectivity.
9. Alumina is beneficial to orbital symmetry-controlled reactions such as Diels-Alder reaction, olefin reaction and Carroll rearrangement. These reaction conditions are mild and have high stereoselectivity. Under the action of Al? O?, S can more easily undergo nucleophilic addition reaction with propylene oxide, and then dehydrate to form alkenes.
10. Alumina catalyzes many rearrangement reactions. Active alumina causes O-sulfonyoximes to undergo Beckmann rearrangement to form the desired amide, while basic alumina produces the corresponding azoline. Under the action of alumina, β, γ-unsaturated ketones can be isomerized to conjugated ketones, alkynes are isomerized to olefins, and olefins are isomerized to conjugated dienolates. Alumina promotes the hydrolysis of primary acetate, deacylation of imides, hydrolysis of sulfonyoximes, and dealkoxy carbonylation of β-ketoates and carbamates.
The above is a detailed introduction to the functions of alumina. In addition to the functions described above, alumina can also be used to strengthen metals. It has good integration with metals and does not chemically react with metals. It is an ideal metal strengthening fiber. However, be careful when using alumina, it can irritate the eyes, skin and respiratory system, and may cause breathing difficulties, so work in a well-ventilated environment.